Event socket

This commit adds a unix socket on which you can receive internal events
as they happen. Currently the only supported event is a chat message
being added. Intended for external applications that depend on chat
messages, e.g. text-to-speech or Twitch Plays Pokémon.

anonstream/__init__.py

@@ -51,6 +51,9 @@ def create_app(config_file):
     # Background tasks' asyncio.sleep tasks, cancelled on shutdown
     app.background_sleep = set()
 
+    # Queues for event socket clients
+    app.event_queues = set()
+
     @app.after_serving
     async def shutdown():
         # Force all background tasks to finish
@@ -60,10 +63,23 @@ def create_app(config_file):
     @app.before_serving
     async def startup():
         # Start control server
-        from anonstream.control.server import start_control_server_at
-        async def start_control_server():
-            return await start_control_server_at(app.config['CONTROL_ADDRESS'])
-        app.add_background_task(start_control_server)
+        if app.config['SOCKET_CONTROL_ENABLED']:
+            from anonstream.control.server import start_control_server_at
+            async def start_control_server():
+                return await start_control_server_at(
+                    app.config['SOCKET_CONTROL_ADDRESS']
+                )
+            app.add_background_task(start_control_server)
+
+        # Start event server
+        if app.config['SOCKET_EVENT_ENABLED']:
+            from anonstream.events import start_event_server_at
+            async def start_event_server():
+                return await start_event_server_at(
+                        app.config['SOCKET_EVENT_ADDRESS']
+                )
+            app.add_background_task(start_event_server)
+
 
         # Create routes and background tasks
         import anonstream.routes

anonstream/chat.py

@@ -7,6 +7,7 @@ from datetime import datetime
 from quart import current_app, escape
 
 from anonstream.broadcast import broadcast, broadcast_users_update
+from anonstream.events import notify_event_sockets
 from anonstream.helpers.chat import generate_nonce_hash, get_scrollback
 from anonstream.utils.chat import get_message_for_websocket, get_approx_linespan
 
@@ -102,6 +103,12 @@ def add_chat_message(user, nonce, comment, ignore_empty=False):
     while len(MESSAGES_BY_ID) > CONFIG['MAX_CHAT_MESSAGES']:
         MESSAGES_BY_ID.pop(last=False)
 
+    # Notify event sockets that a chat message was added
+    notify_event_sockets({
+        'type': 'message',
+        'event': message,
+    })
+
     # Broadcast a users update to all websockets,
     # in case this message is from a new user
     broadcast_users_update()

anonstream/config.py

@@ -13,7 +13,6 @@ def update_flask_from_toml(toml_config, flask_config):
     flask_config.update({
         'SECRET_KEY_STRING': toml_config['secret_key'],
         'SECRET_KEY': toml_config['secret_key'].encode(),
-        'CONTROL_ADDRESS': toml_config['control']['address'],
         'AUTH_USERNAME': toml_config['auth']['username'],
         'AUTH_PWHASH': auth_pwhash,
         'AUTH_TOKEN': generate_token(),
@@ -25,6 +24,7 @@ def update_flask_from_toml(toml_config, flask_config):
 
 def toml_to_flask_sections(config):
     TOML_TO_FLASK_SECTIONS = (
+        toml_to_flask_section_socket,
         toml_to_flask_section_segments,
         toml_to_flask_section_title,
         toml_to_flask_section_names,
@@ -38,6 +38,15 @@ def toml_to_flask_sections(config):
     for toml_to_flask_section in TOML_TO_FLASK_SECTIONS:
         yield toml_to_flask_section(config)
 
+def toml_to_flask_section_socket(config):
+    cfg = config['socket']
+    return {
+        'SOCKET_CONTROL_ENABLED': cfg['control']['enabled'],
+        'SOCKET_CONTROL_ADDRESS': cfg['control']['address'],
+        'SOCKET_EVENT_ENABLED': cfg['event']['enabled'],
+        'SOCKET_EVENT_ADDRESS': cfg['event']['address'],
+    }
+
 def toml_to_flask_section_segments(config):
     cfg = config['segments']
     return {

anonstream/events.py

@@ -0,0 +1,30 @@
+import asyncio
+import json
+
+from quart import current_app
+
+async def start_event_server_at(address):
+    return await asyncio.start_unix_server(serve_event_client, address)
+
+async def serve_event_client(reader, writer):
+    reader.feed_eof()
+    queue = asyncio.Queue()
+    current_app.event_queues.add(queue)
+    try:
+        while True:
+            event = await queue.get()
+            event_json = json.dumps(event, separators=(',', ':'))
+            writer.write(event_json.encode())
+            writer.write(b'\n')
+            try:
+                await writer.drain()
+            # Because we used reader.feed_eof(), if the client sends anything
+            # an AsserionError will be raised
+            except (ConnectionError, AssertionError):
+                break
+    finally:
+        current_app.event_queues.remove(queue)
+
+def notify_event_sockets(event):
+    for queue in current_app.event_queues:
+        queue.put_nowait(event)

anonstream/helpers/chat.py

@@ -9,7 +9,7 @@ CONFIG = current_app.config
 
 def generate_nonce_hash(nonce):
     parts = CONFIG['SECRET_KEY'] + b'nonce-hash\0' + nonce.encode()
-    return hashlib.sha256(parts).digest()
+    return hashlib.sha256(parts).hexdigest()
 
 def get_scrollback(messages):
     n = CONFIG['MAX_CHAT_SCROLLBACK']

config.toml

@@ -1,8 +1,13 @@
 secret_key = "place secret key here"
 
-[control]
+[socket.control]
+enabled = true
 address = "control.sock"
 
+[socket.event]
+enabled = true
+address = "event.sock"
+
 [auth]
 username = "broadcaster"